This study examines the intergenerational transmission of risk for drug use in a three-generation prospective design. The children of the initial subjects of the Rochester Youth Development Study are focal subjects of this long-term study, allowing us to examine two general issues. The first is to describe intergenerational continuity and discontinuity across the generations for drug use and related problem behaviors, including delinquency, depression, and health-risking behaviors for HIV/AIDS. The second is to identify mediating processes to explain both intergenerational continuity and intergenerational discontinuity in drug use and co-morbid behaviors. Because our initial sample included both males and females, we can examine these issues for fathers as well as mothers. By nesting this intergenerational study within a long-term panel study, we can greatly broaden the range of the explanatory variables used to investigate drug use. We capitalize on the developmental data collected since 1988 on both the parents and grandparents of these focal subjects; combining these data with the prospective data collected in the intergenerational study provides an opportunity to examine how the parent's own developmental course influences their transition to adulthood and their behavior as parents which, in turn, can be used to explain the onset and development of the child's drug use and related problem behaviors. In Year 1 (1999) we selected G3 children 2 years of age and older (n=371), and we continue to add new 2-year-olds each year. By Year 12, we will have a total sample of approximately 487. Annually, we interview the parent who has been a member of the Rochester Youth Development Study since 1988, the child's other primary caregiver, and the G3 child (age 8 and older). For three assessments, we observe dyadic interactions between the child and each of these caregivers. Data are collected from teachers, schools, and other agencies. Measures include the young parent's structural position and stressors, drug use and problem behaviors, prosocial bonds, peer friendship networks, and parenting behaviors. The manner, in which these attributes unfold over the parent's life course, as well as their own adolescent development, will be used to explain the development of the child's drug use, related problem behaviors, and prosocial competencies.